This document specifies a reference set of Label Generation Rules (LGR) for the Bengali (Bangla) script. This LGR covers Assamese, Bengali, Manipuri and a number of other languages written with the Bengali script. The starting point for the development of this LGR can be found in the related Root Zone LGR [RZ-LGR-3-Beng]. For details and additional background on the script, see "Proposal for a Bengali Script Root Zone Label Generation Ruleset (LGR)" [Proposal-Bengali]. The format of this file follows [RFC 7940].
This is a DRAFT document released for public comments and not final. Please see the announcement on the ICANN website for public comments on the Second Level Reference LGRs for details on how to submit comments.
The repertoire contains 61 code points for letters, as well as 9 code point sequences. Out of the nine sequences: two sequences override a WLE constraint; four sequences were defined for in-script variants; and the other three sequences were defined to restrict U+09BC NUKTA from appearing in any context other than these sequences. Accordingly, while U+09BC is not listed by itself, it brings the total of code points available for letters to 62. For more detail, see Section 5, "Repertoire" in [Proposal-Bengali]. (The proposal cited has been adopted for the Bengali script portion of the Root Zone LGR.)
For the second level, the repertoire has been augmented with the Bengali digits, U+09E6 to U+09EF, ASCII digits U+0030 to U+0039, and U+002D HYPHEN-MINUS for a total of 91 repertoire elements.
Code points outside the Bengali script that are listed in this file are targets for out-of-script variants and are identified by a reflexive (identity) variant of type "out-of-repertoire-var". They do not form part of the repertoire.
Each code point or range is tagged with the script or scripts that the code point is used with, one or more tag values denoting character category, and one or more references documenting sufficient justification for inclusion in the repertoire; see "References" below. For code points that are part of the repertoire, comments identify the languages using the code point.
This reference LGR is designed for use in zones shared by more than one script. Where appropriate, cross-script variants have been defined to mutually exclude labels from different scripts that could otherwise be substituted by the users. Once a label has been delegated for one script, any variant labels from other scripts consisting of cross-script variants would be blocked. Any label containing at least one code point that is not a cross-script variant would be considered distinct. Because of that, even large numbers of defined cross-script variants generally do not lead to a high percentage of labels experiencing a collision.
This LGR defines in-script variants and cross-script variants as described in Section 6, "Variants" in [Proposal-Bengali]. There are three in-script variants; two sequence sets and one set for variation of RA. See Section 6.1 in [Proposal-Bengali]. There are four cross-script variants; two sets with Gurmukhi and the other two sets with Devanagari. See Section 6.2 in [Proposal-Bengali].
Digit Variants: All Bengali digits are treated as semantic variants of the corresponding common (ASCII) digits. By transitivity, they are also semantic variants of any native digits in scripts that also include the common digits. Such variant relations are deemed to exist implicitly by transitivity but are not listed explicitly in each reference LGR. (Omitting the listing of these other cross script digit variants does not affect index variant calculation, as the ASCII digit variant being smallest would always be the index variant.) Bengali digit ZERO is a cross-script homoglyph or near homoglyph of digit ZERO in many other scripts; these are already implicit semantic variants by transitivity and therefore not listed here. To keep digit variant sets manageable in zones where multiple scripts are present, no attempt has been made at identifying cross-script variants among digits of different numeric value, such as between Bengali digit SEVEN and Gujarati digit ONE; or between a digit in one script and a letter in another, such as between digit zero and Latin letter 'o'.
Variant Disposition: The in-script variant pair U+09B0 / U+09F0 is of type "allocatable", thus allowing access to either user community. All other variants are of type "blocked", making labels that differ only by these variants mutually exclusive: whichever label containing either of these variants is chosen earlier, the other one equivalent variant label should be blocked. There is no preference among these variants.
The specification of variants in this reference LGR follows the guidelines in [RFC 8228].
Consonants: All consonants contain an implicit vowel. More details in Section 3.3.1, " The Consonants" of [Proposal-Bengali].
Hasanta: A special sign is needed whenever the implicit vowel in the preceding consonant is stripped off. This symbol is also known as the Halant or "Virama". More details in Section 3.3.2, "The Implicit Vowel Killer: Hasanta" of [Proposal-Bengali].
Vowels: Separate symbols exist for all "Swara" or Vowels in Bengali, which are pronounced independently either at the beginning of the word or after another vowel or consonant sound. To indicate a Vowel sound other than the implicit one, a Vowel sign (Matra) is attached to the consonant. More details in Section 3.3.3, "Vowels" of [Proposal-Bengali].
Anusvara: The Anusvara represents a homorganic nasal. It replaces a conjunct group of a Nasal Consonant+Halant+Consonant belonging to that particular barga or set. Before a non-barga consonant, the anusvara represents a nasal sound. More details in Section 3.3.4, "The Anusvara" of [Proposal-Bengali].
Candrabindu: Candrabindu denotes nasalization of the preceding vowel as in চাঁদ /cãd/ "moon" (U+099A U+09BE U+0981 U+09A6). This sign with a dot inside the half-moon mark is used as nasalization marker in many Indian scripts. More details in Section 3.3.5, "Nasalization: Candrabindu" of [Proposal-Bengali].
Visarga and Avagraha: The Visarga U+0983 is frequently used in Bengali loanwords borrowed from Sanskrit and represents a sound very close to /h/. More details in Section 3.3.7, "Visarga and Avagraha" of [Proposal-Bengali].
Ya-phala: There are two instances in Bangla where a Hasanta is preceded by a full vowel (U+0985 BENGALI LETTER A and U+098F BENGALI LETTER E). More details in Section 3.3.9, "Use of Ya-phala" of [Proposal-Bengali].
Ra-phala and Ref Sequences: RA+Hasanta (Repha or Ra-phala sequences). More details in Section 3.3.10, "Ra-phala and Ref Sequences" of [Proposal-Bengali].
Nukta: Nukta is not listed by itself in the repertoire; it is only included in three sequences. More details in Section 3.3.6, "Nukta" of [Proposal-Bengali].
Zero Width Non-joiner (ZWNJ) and Zero Width Joiner (ZWJ): These are not included in the repertoire. More details in Section 3.3.8, "Zero Width Non-joiner (U+200C) and Zero Width Joiner (U+200D)" of [Proposal-Bengali].
Bengali Digits: U+09E6 to U+09EF are a set of Bengali-specific digits. They are used in alternation with the European (common) digits.
Common Digits: U+0030 to U+0039 are the set of digits from the ASCII range.
Actions include the default actions for LGRs as well as that needed to invalidate labels with misplaced combining marks. They are marked with ⍟. For a description see [RFC 7940].
These rules have been formulated as context rules suitable for adoption into an LGR specification.
The following symbols are used in the WLE rules:
The rules are:
More details in Section 7, "Whole Label Evaluation Rules (WLE)" of [Proposal-Bengali].
This reference LGR for Bengali for the 2nd Level has been developed by Michel Suignard and Asmus Freytag, based on the Root Zone LGR for Bengali and information contained or referenced therein, see [RZ-LGR-3-Beng]. Suitable extensions for the second level have been applied according to the [Guidelines]. The original proposal for a Root Zone LGR for the Bengali script, that this reference LGR is based on, was developed by the Neo-Brahmi Generation Panel (NBGP). For more information on methodology and contributors to the underlying Root Zone LGR, see Sections 4 and 8 in [Proposal-Bengali], as well as [RZ-LGR-Overview].
The following general references are cited in this document:
For references consulted particularly in designing the repertoire for the Bengali script for the second level please see details in the Table of References below. References [0] and [7] refer to the Unicode Standard versions in which the corresponding code points were initially encoded. References [101] and above correspond to sources given in [Proposal-Bengali] justifying the inclusion of the corresponding code points. Entries in the table may have multiple source reference values.
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